I certainly can see excluding SOHO, with all of its specialized
problems. There is a remaining concern for large enterprises and
hosting centers with gigabit Ethernet or POS/SONET/SDH acceess to
their upstream IP providers. The huge bandwidth available to certain
organization could make them, if compromised by miscreants, huge
threats to SP network stability.
To protect the SP network from a compromised high-bandwidth site,
security measures may be implemented in provider-operated equipment
at the site, or, more likely, at the POP. As a rule of thumb, if a
given site has bandwidth comparable to a midsize ISP, I believe it
has to be given special consideration as a risk, and also a major
revenue source to be protected.